<?php
// RSS 0.90  Officially obsoleted by 1.0
// RSS 0.91, 0.92, 0.93 and 0.94  Officially obsoleted by 2.0
// So, define constants for RSS 1.0, RSS 2.0 and ATOM

	define('RSS1', 'RSS 1.0', true);
	define('RSS2', 'RSS 2.0', true);
	define('ATOM', 'ATOM', true);

 /**
 * Univarsel Feed Writer class
 *
 * Genarate RSS 1.0, RSS2.0 and ATOM Feed
 *
 * @package     UnivarselFeedWriter
 * @author      Anis uddin Ahmad <anisniit@gmail.com>
 * @link        http://www.ajaxray.com/projects/rss
 */
 class FeedWriter
 {
	 private $channels      = array();  // Collection of channel elements
	 private $items         = array();  // Collection of items as object of FeedItem class.
	 private $data          = array();  // Store some other version wise data
	 private $CDATAEncoding = array();  // The tag names which have to encoded as CDATA

	 private $version   = null;

	/**
	* Constructor
	*
	* @param    constant    the version constant (RSS1/RSS2/ATOM).
	*/
	function __construct($version = RSS2)
	{
		$this->version = $version;

		// Setting default value for assential channel elements
		$this->channels['title']        = $version . ' Feed';
		$this->channels['link']         = 'http://www.ajaxray.com/blog';

		//Tag names to encode in CDATA
		$this->CDATAEncoding = array('description', 'content:encoded', 'summary');
	}

	// Start # public functions ---------------------------------------------

	/**
	* Set a channel element
	* @access   public
	* @param    srting  name of the channel tag
	* @param    string  content of the channel tag
	* @return   void
	*/
	public function setChannelElement($elementName, $content)
	{
		$this->channels[$elementName] = $content ;
	}

	/**
	* Set multiple channel elements from an array. Array elements
	* should be 'channelName' => 'channelContent' format.
	*
	* @access   public
	* @param    array   array of channels
	* @return   void
	*/
	public function setChannelElementsFromArray($elementArray)
	{
		if(! is_array($elementArray)) return;
		foreach ($elementArray as $elementName => $content)
		{
			$this->setChannelElement($elementName, $content);
		}
	}

	/**
	* Genarate the actual RSS/ATOM file
	*
	* @access   public
	* @return   void
	*/
	public function genarateFeed()
	{
		header("Content-type: text/xml");

		$this->printHead();
		$this->printChannels();
		$this->printItems();
		$this->printTale();
	}

	/**
	* Create a new FeedItem.
	*
	* @access   public
	* @return   object  instance of FeedItem class
	*/
	public function createNewItem()
	{
		$Item = new FeedItem($this->version);
		return $Item;
	}

	/**
	* Add a FeedItem to the main class
	*
	* @access   public
	* @param    object  instance of FeedItem class
	* @return   void
	*/
	public function addItem($feedItem)
	{
		$this->items[] = $feedItem;
	}


	// Wrapper functions -------------------------------------------------------------------

	/**
	* Set the 'title' channel element
	*
	* @access   public
	* @param    srting  value of 'title' channel tag
	* @return   void
	*/
	public function setTitle($title)
	{
		$this->setChannelElement('title', $title);
	}

	/**
	* Set the 'description' channel element
	*
	* @access   public
	* @param    srting  value of 'description' channel tag
	* @return   void
	*/
	public function setDescription($desciption)
	{
		$this->setChannelElement('description', $desciption);
	}

	/**
	* Set the 'link' channel element
	*
	* @access   public
	* @param    srting  value of 'link' channel tag
	* @return   void
	*/
	public function setLink($link)
	{
		$this->setChannelElement('link', $link);
	}

	/**
	* Set the 'image' channel element
	*
	* @access   public
	* @param    srting  title of image
	* @param    srting  link url of the imahe
	* @param    srting  path url of the image
	* @return   void
	*/
	public function setImage($title, $link, $url)
	{
		$this->setChannelElement('image', array('title'=>$title, 'link'=>$link, 'url'=>$url));
	}

	/**
	* Set the 'about' channel element. Only for RSS 1.0
	*
	* @access   public
	* @param    srting  value of 'about' channel tag
	* @return   void
	*/
	public function setChannelAbout($url)
	{
		$this->data['ChannelAbout'] = $url;
	}

  /**
  * Genarates an UUID
  * @author     Anis uddin Ahmad <admin@ajaxray.com>
  * @param      string  an optional prefix
  * @return     string  the formated uuid
  */
  public function uuid($key = null, $prefix = '')
  {
	$key = ($key == null)? uniqid(rand()) : $key;
	$chars = md5($key);
	$uuid  = substr($chars,0,8) . '-';
	$uuid .= substr($chars,8,4) . '-';
	$uuid .= substr($chars,12,4) . '-';
	$uuid .= substr($chars,16,4) . '-';
	$uuid .= substr($chars,20,12);

	return $prefix . $uuid;
  }
	// End # public functions ----------------------------------------------

	// Start # private functions ----------------------------------------------

	/**
	* Prints the xml and rss namespace
	*
	* @access   private
	* @return   void
	*/
	private function printHead()
	{
		$out  = '<?xml version="1.0" encoding="utf-8"?>' . "\n";

		if($this->version == RSS2)
		{
			$out .= '<rss version="2.0"
					xmlns:content="http://purl.org/rss/1.0/modules/content/"
					xmlns:wfw="http://wellformedweb.org/CommentAPI/"
				  >' . PHP_EOL;
		}
		elseif($this->version == RSS1)
		{
			$out .= '<rdf:RDF
					 xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#"
					 xmlns="http://purl.org/rss/1.0/"
					 xmlns:dc="http://purl.org/dc/elements/1.1/"
					>' . PHP_EOL;;
		}
		else if($this->version == ATOM)
		{
			$out .= '<feed xmlns="http://www.w3.org/2005/Atom">' . PHP_EOL;;
		}
		echo $out;
	}

	/**
	* Closes the open tags at the end of file
	*
	* @access   private
	* @return   void
	*/
	private function printTale()
	{
		if($this->version == RSS2)
		{
			echo '</channel>' . PHP_EOL . '</rss>';
		}
		elseif($this->version == RSS1)
		{
			echo '</rdf:RDF>';
		}
		else if($this->version == ATOM)
		{
			echo '</feed>';
		}

	}

	/**
	* Creates a single node as xml format
	*
	* @access   private
	* @param    srting  name of the tag
	* @param    mixed   tag value as string or array of nested tags in 'tagName' => 'tagValue' format
	* @param    array   Attributes(if any) in 'attrName' => 'attrValue' format
	* @return   string  formatted xml tag
	*/
	private function makeNode($tagName, $tagContent, $attributes = null)
	{
		$nodeText = '';
		$attrText = '';

		if(is_array($attributes))
		{
			foreach ($attributes as $key => $value)
			{
				$attrText .= " $key=\"$value\" ";
			}
		}

		if(is_array($tagContent) && $this->version == RSS1)
		{
			$attrText = ' rdf:parseType="Resource"';
		}


		$attrText .= (in_array($tagName, $this->CDATAEncoding) && $this->version == ATOM)? ' type="html" ' : '';
		$nodeText .= (in_array($tagName, $this->CDATAEncoding))? "<{$tagName}{$attrText}><![CDATA[" : "<{$tagName}{$attrText}>";

		if(is_array($tagContent))
		{
			foreach ($tagContent as $key => $value)
			{
				$nodeText .= $this->makeNode($key, $value);
			}
		}
		else
		{
			$nodeText .= (in_array($tagName, $this->CDATAEncoding))? $tagContent : htmlentities($tagContent, ENT_QUOTES, 'UTF-8');
		}

		$nodeText .= (in_array($tagName, $this->CDATAEncoding))? "]]></$tagName>" : "</$tagName>";

		return $nodeText . PHP_EOL;
	}

	/**
	* @desc     Print channels
	* @access   private
	* @return   void
	*/
	private function printChannels()
	{
		//Start channel tag
		switch ($this->version)
		{
		   case RSS2:
				echo '<channel>' . PHP_EOL;
				break;
		   case RSS1:
				echo (isset($this->data['ChannelAbout']))? "<channel rdf:about=\"{$this->data['ChannelAbout']}\">" : "<channel rdf:about=\"{$this->channels['link']}\">";
				break;
		}

		//Print Items of channel
		foreach ($this->channels as $key => $value)
		{
			if($this->version == ATOM && $key == 'link')
			{
				// ATOM prints link element as href attribute
				echo $this->makeNode($key,'',array('href'=>$value));
				//Add the id for ATOM
				echo $this->makeNode('id',$this->uuid($value,'urn:uuid:'));
			}
			else
			{
				echo $this->makeNode($key, $value);
			}

		}

		//RSS 1.0 have special tag <rdf:Seq> with channel
		if($this->version == RSS1)
		{
			echo "<items>" . PHP_EOL . "<rdf:Seq>" . PHP_EOL;
			foreach ($this->items as $item)
			{
				$thisItems = $item->getElements();
				echo "<rdf:li resource=\"{$thisItems['link']['content']}\"/>" . PHP_EOL;
			}
			echo "</rdf:Seq>" . PHP_EOL . "</items>" . PHP_EOL . "</channel>" . PHP_EOL;
		}
	}

	/**
	* Prints formatted feed items
	*
	* @access   private
	* @return   void
	*/
	private function printItems()
	{
		foreach ($this->items as $item)
		{
			$thisItems = $item->getElements();

			//the argument is printed as rdf:about attribute of item in rss 1.0
			echo $this->startItem($thisItems['link']['content']);

			foreach ($thisItems as $feedItem )
			{
				echo $this->makeNode($feedItem['name'], $feedItem['content'], $feedItem['attributes']);
			}
			echo $this->endItem();
		}
	}

	/**
	* Make the starting tag of channels
	*
	* @access   private
	* @param    srting  The vale of about tag which is used for only RSS 1.0
	* @return   void
	*/
	private function startItem($about = false)
	{
		if($this->version == RSS2)
		{
			echo '<item>' . PHP_EOL;
		}
		elseif($this->version == RSS1)
		{
			if($about)
			{
				echo "<item rdf:about=\"$about\">" . PHP_EOL;
			}
			else
			{
				die('link element is not set .\n It\'s required for RSS 1.0 to be used as about attribute of item');
			}
		}
		else if($this->version == ATOM)
		{
			echo "<entry>" . PHP_EOL;
		}
	}

	/**
	* Closes feed item tag
	*
	* @access   private
	* @return   void
	*/
	private function endItem()
	{
		if($this->version == RSS2 || $this->version == RSS1)
		{
			echo '</item>' . PHP_EOL;
		}
		else if($this->version == ATOM)
		{
			echo "</entry>" . PHP_EOL;
		}
	}



	// End # private functions ----------------------------------------------

 } // end of class FeedWriter

// autoload classes
function __autoload($class_name)
{
	require_once $class_name . '.php';
}
